Parkinson's Disease (PD) is a chronic, progressive motor system disorder. Approximately 50,000 Americans are diagnosed with PD each year. The primary symptoms of this neurodegenerative disease are trembling, rigidity, slowness of movement, and impaired balance. In addition, many PD patients experience a variety of other symptoms, including emotional changes, memory loss, speech problems, or difficulty sleeping.
PD is caused by specific and progressive neuronal loss of mid-brain dopamine (DA) neurons. Ordinarily, these neurons produce dopamine, a chemical messenger responsible for transmitting signals between the substantia nigra and the corpus striatum, resulting in smooth, purposeful muscle activity. However, loss of dopamine causes the nerve cells of the striatum to fire in an uncontrolled manner, leaving patients with impaired ability to direct and control their movements.
Current therapy for PD relies heavily on replenishing dopamine by giving patients oral doses of the dopamine precursor L-DOPA (L-dihydroxyphenyl-alanine). This therapy requires increasing doses as treatment continues, and it eventually elicits serious side effects. There is a need for additional therapeutics for PD.